1. Field of the invention
This invention relates to a novel thermoplastic resin composition suitable for preparing shaped articles by injection molding or extrusion molding.
2. Related Art
Generally, polyphenylene ether is a resin superior in heat resistance, hot water resistance, dimensional stability, various mechanical properties, electrical properties and the like but on the other hand it has disadvantages in that it is inferior not only in processability due to its high melt viscosity but also inferior in chemical resistance and impact resistance.
A composite material comprising polyphenylene ether and polystyrene is proposed in order to lessen melt viscosity of polyphenylene ether and to improve processability thereof, leaving various other good properties of polyphenylene ether unchanged. However, its chemical resistance still remains to be improved.
On the other hand, propylene polymer is a familiar material for preparing various shaped articles, film and sheet since it is superior in processability, toughness, water resistance and chemicaI resistance, as well as it has low specific gravity and is inexpensive. However, propylene polymer has problems in heat resistance, rigidity, impact resistance, coatability, adhesiveness and the like, which is an obstacle to development of new practical application thereof. Therefore, there is a keen desire for improvement of its properties, among others, heat resistance and impact resistance.
Accordingly, development is expected in new application to a variety of utility if a resin composition is prepared in which polyphenylene ether and propylene polymer are blended, maintaining favorite properties of both components and having improved processability and impact resistance. However, in actuality, the blending of propylene polymer with polyphenylene ether results in poor compatibility, and shaped articles which can be obtained by injection molding the blended composition show phase separation between polyphenylene and propylene polymer, thus giving rise to only those shaped articles which have poor appearance and inferior mechanical properties; they are unacceptable for practical purposes. However, there is on the market increasing demand for a resin composition which retains excellent heat resistance ascribable to polyphenylene ether and also high impact resistance and superior weatherability and coatability.